Hi, Harsha, I am still looking at the KIP and the PR. A couple of quick comments/questions.
20. It's fine to keep the HDFS binding temporarily in the PR. We just need to remove it before it's merged to trunk. As Victor mentioned, we can provide a reference implementation based on a mocked version of remote storage. 21. I am not sure that I understood the need for RemoteLogIndexEntry and its relationship with RemoteLogSegmentInfo. It seems that RemoteLogIndexEntry are offset index entries pointing to record batches inside a segment. That seems to be the same as the .index file? Thanks, Jun On Mon, Oct 28, 2019 at 9:11 PM Satish Duggana <satish.dugg...@gmail.com> wrote: > Hi Viktor, > >1. Can we allow RLM Followers to serve read requests? After all segments > on > the cold storage are closed ones, no modification is allowed. Besides > KIP-392 ( > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-392%3A+Allow+consumers+to+fetch+from+closest+replica > ) > would introduce follower fetching too, so I think it would be nice to > prepare RLM for this as well. > > That is a good point. We plan to support fetching remote storage from > followers too. Current code in the PR work fine for this scenario > though there may be some edge cases to be handled. We have not yet > tested this scenario. > > >2. I think the remote.log.storage.enable config is redundant. By > specifying > remote.log.storage.manager.class.name one already declares that they want > to use remote storage. Would it make sense to remove > the remote.log.storage.enable config? > > I do not think it is really needed. `remote.log.storage.enable` > property can be removed. > > Thanks, > Satish. > > > On Thu, Oct 24, 2019 at 2:46 PM Viktor Somogyi-Vass > <viktorsomo...@gmail.com> wrote: > > > > Hi Harsha, > > > > A couple more questions: > > 1. Can we allow RLM Followers to serve read requests? After all segments > on > > the cold storage are closed ones, no modification is allowed. Besides > > KIP-392 ( > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-392%3A+Allow+consumers+to+fetch+from+closest+replica > ) > > would introduce follower fetching too, so I think it would be nice to > > prepare RLM for this as well. > > 2. I think the remote.log.storage.enable config is redundant. By > specifying > > remote.log.storage.manager.class.name one already declares that they > want > > to use remote storage. Would it make sense to remove > > the remote.log.storage.enable config? > > > > Thanks, > > Viktor > > > > > > On Thu, Oct 24, 2019 at 10:37 AM Viktor Somogyi-Vass < > > viktorsomo...@gmail.com> wrote: > > > > > Hi Jun & Harsha, > > > > > > I think it would be beneficial to at least provide one simple reference > > > implementation (file system based?) as we do with connect too. > > > That would as a simple example and would help plugin developers to > better > > > understand the concept and the interfaces. > > > > > > Best, > > > Viktor > > > > > > On Wed, Oct 23, 2019 at 8:49 PM Jun Rao <j...@confluent.io> wrote: > > > > > >> Hi, Harsha, > > >> > > >> Regarding feature branch, if the goal is faster collaboration, it > seems > > >> that doing the development on your own fork is better since > non-committers > > >> can push changes there. > > >> > > >> Regarding the dependencies, this is an important thing to clarify. My > > >> understanding for this KIP is that in Apache Kafka, we won't provide > any > > >> specific implementation for a particular block storage. There are many > > >> block storage systems out there (HDFS, S3, Google storage, Azure > storage, > > >> Ceph, etc). We don't want to drag in all those dependencies in Apache > > >> Kafka, even if they are in a separate module. Doing that will make the > > >> Kafka repo much harder to manage. We have used the same approach for > > >> connect. The connect framework is in Apache Kafka, but all specific > > >> connectors are hosted externally. > > >> > > >> Thanks, > > >> > > >> Jun > > >> > > >> > > >> > > >> On Wed, Oct 23, 2019 at 8:41 AM Eno Thereska <eno.there...@gmail.com> > > >> wrote: > > >> > > >> > Thanks Satish, Harsha, > > >> > > > >> > It's probably worth it making it clearer in the KIP what exact > > >> > libraries will be added to libs, if any. The KIP specifies the > remote > > >> > storage interface but it isn't clear if particular implementations > > >> > will be added to Kafka's repository or whether they will reside in > > >> > other repositories. If I understand the intention correctly, you are > > >> > proposing to have an HDFS and S3 implementation as part of the Kafka > > >> > repository working out of the box. Is that correct? > > >> > > > >> > Thanks > > >> > Eno > > >> > > > >> > On Wed, Oct 23, 2019 at 5:01 AM Satish Duggana < > > >> satish.dugg...@gmail.com> > > >> > wrote: > > >> > > > > >> > > >Regarding the HDFS dependency its not a direct dependency rather > > >> > > its implementing the RemoteStorageManager interface. > > >> > > We packaged it along with core to make it more convenient to test > it. > > >> We > > >> > > can move this to external module and keep it there. > > >> > > Let me know what you think. > > >> > > > > >> > > Let me elaborate more on this point. With the new changes in the > PR, > > >> > > kafka core or any other existing module is not dependent on HDFS. > We > > >> > > created a new module called `remote-storage-managers/hdfs`. > Libraries > > >> > > generated by this module are added to libs while packaging the > > >> > > distribution. This makes easy for users to try HDFS tiered storage > > >> > > instead of users building hdfs module and add it to libs on their > own. > > >> > > We have plans to push these libs into external/libs/ directory and > > >> > > they will not be added to the classpath by default. We can add > them to > > >> > > the classpath in scripts based on a system property. > > >> > > > > >> > > On Wed, Oct 23, 2019 at 6:26 AM Harsha Chintalapani < > ka...@harsha.io> > > >> > wrote: > > >> > > > > > >> > > > Hi Jun, > > >> > > > Thanks for the feedback. Given the no.of engineers > > >> involved > > >> > in > > >> > > > cross-team effort > > >> > > > it would be great to have this as feature branch. Irrespective > of if > > >> > its in > > >> > > > my fork > > >> > > > or in Apache Kafka's branch it needs to be constantly rebased > from > > >> > trunk to > > >> > > > keep it current. > > >> > > > Our proposal is to merge it in feature branch and open a PR so > its > > >> no > > >> > > > different than current PR except that > > >> > > > its in central repo rather my fork. Having it in Kafka's branch > > >> > > > makes it easier for everyone to collaborate on this important > > >> feature > > >> > in > > >> > > > kafka. Let me know if you still think otherwise. > > >> > > > KIP is updated and we can go through the discussion. > > >> > > > Regarding the HDFS dependency its not a direct > dependency > > >> > rather > > >> > > > its implementing the RemoteStorageManager interface. > > >> > > > We packaged it along with core to make it more convenient to > test > > >> it. > > >> > We > > >> > > > can move this to external module and keep it there. > > >> > > > Let me know what you think. > > >> > > > > > >> > > > Thanks, > > >> > > > Harsha > > >> > > > > > >> > > > On Tue, Oct 22, 2019 at 3:53 PM Jun Rao <j...@confluent.io> > wrote: > > >> > > > > > >> > > > > Hi, Harsha, > > >> > > > > > > >> > > > > Historically, we tried using a feature branch in 0.8. The > > >> experience > > >> > > > > actually wasn't great. Merging the feature branch to the main > > >> branch > > >> > > > > required additional review work and each merge with the main > > >> branch > > >> > added > > >> > > > > the risk of introducing new bugs. So, we have been avoiding > > >> feature > > >> > > > > branches since then, even for some major features. > > >> > > > > > > >> > > > > It's also going to be weird to have a feature branch before a > KIP > > >> is > > >> > > > > accepted. > > >> > > > > > > >> > > > > The KIP hasn't been updated much since the initial reviews. > Is it > > >> > ready for > > >> > > > > discussion again? > > >> > > > > > > >> > > > > Looking at the PR, it seems to have direct dependency on > HDFS. My > > >> > > > > understanding is that the goal of the KIP is to make it more > > >> general > > >> > such > > >> > > > > that it can bind to different types of block storage. If so, > we > > >> > should > > >> > > > > avoid introducing a direct dependency to any specific block > > >> storage > > >> > in > > >> > > > > Apache Kafka. > > >> > > > > > > >> > > > > Thanks, > > >> > > > > > > >> > > > > Jun > > >> > > > > > > >> > > > > On Mon, Oct 21, 2019 at 8:46 AM Harsha <ka...@harsha.io> > wrote: > > >> > > > > > > >> > > > > > Hi All, > > >> > > > > > Thanks for the initial feedback on the KIP-405. > We > > >> > opened a PR > > >> > > > > > here https://github.com/apache/kafka/pull/7561 . > > >> > > > > > Please take a look and let us know if you have any > questions. > > >> > > > > > Since this feature is being developed by engineers from > > >> different > > >> > > > > > companies we would like to open a feature branch in apache > kafka > > >> > git. It > > >> > > > > > will allow us collaborate in open source community rather > than > > >> in > > >> > private > > >> > > > > > branches. Please let me know if you have any objections to > > >> opening > > >> > a > > >> > > > > > feature branch in kafka's git repo. > > >> > > > > > > > >> > > > > > Thanks, > > >> > > > > > Harsha > > >> > > > > > > > >> > > > > > On Mon, Apr 8, 2019, at 10:04 PM, Harsha wrote: > > >> > > > > > > Thanks, Ron. Updating the KIP. will add answers here as > well > > >> > > > > > > > > >> > > > > > > 1) If the cold storage technology can be cross-region, is > > >> there > > >> > a > > >> > > > > > > possibility for a disaster recovery Kafka cluster to > share > > >> the > > >> > > > > messages > > >> > > > > > in > > >> > > > > > > cold storage? My guess is the answer is no, and messages > > >> > replicated > > >> > > > > to > > >> > > > > > the > > >> > > > > > > D/R cluster have to be migrated to cold storage from > there > > >> > > > > > independently. > > >> > > > > > > (The same cross-region cold storage medium could be > used, but > > >> > every > > >> > > > > > message > > >> > > > > > > would appear there twice). > > >> > > > > > > > > >> > > > > > > If I understand the question correctly, what you are > saying is > > >> > Kafka A > > >> > > > > > > cluster (active) shipping logs to remote storage which > > >> > cross-region > > >> > > > > > > replication and another Kafka Cluster B (Passive) will it > be > > >> > able to > > >> > > > > > > use the remote storage copied logs directly. > > >> > > > > > > For the initial version my answer is No. We can handle > this in > > >> > > > > > > subsequent changes after this one. > > >> > > > > > > > > >> > > > > > > 2) Can/should external (non-Kafka) tools have direct > access > > >> to > > >> > the > > >> > > > > > messages > > >> > > > > > > in cold storage. I think this might have been addressed > when > > >> > someone > > >> > > > > > asked > > >> > > > > > > about ACLs, and I believe the answer is "no" -- if some > > >> > external tool > > >> > > > > > needs > > >> > > > > > > to operate on that data then that external tool should > read > > >> > that data > > >> > > > > by > > >> > > > > > > acting as a Kafka consumer. Again, just asking to get the > > >> answer > > >> > > > > clearly > > >> > > > > > > documented in case it is unclear. > > >> > > > > > > > > >> > > > > > > The answer is No. All tools/clients must go through broker > > >> APIs > > >> > to > > >> > > > > > > access any data (local or remote). > > >> > > > > > > Only Kafka broker user will have access to remote storage > logs > > >> > and > > >> > > > > > > Security/ACLs will work the way it does today. > > >> > > > > > > Tools/Clients going directly to the remote storage might > help > > >> in > > >> > terms > > >> > > > > > > of efficiency but this requires Protocol changes and some > way > > >> of > > >> > > > > > > syncing ACLs in Kafka to the Remote storage. > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > Thanks, > > >> > > > > > > Harsha > > >> > > > > > > > > >> > > > > > > On Mon, Apr 8, 2019, at 8:48 AM, Ron Dagostino wrote: > > >> > > > > > > > Hi Harsha. A couple of questions. I think I know the > > >> > answers, but > > >> > > > > it > > >> > > > > > > > would be good to see them explicitly documented. > > >> > > > > > > > > > >> > > > > > > > 1) If the cold storage technology can be cross-region, > is > > >> > there a > > >> > > > > > > > possibility for a disaster recovery Kafka cluster to > share > > >> the > > >> > > > > > messages in > > >> > > > > > > > cold storage? My guess is the answer is no, and > messages > > >> > replicated > > >> > > > > > to the > > >> > > > > > > > D/R cluster have to be migrated to cold storage from > there > > >> > > > > > independently. > > >> > > > > > > > (The same cross-region cold storage medium could be > used, > > >> but > > >> > every > > >> > > > > > message > > >> > > > > > > > would appear there twice). > > >> > > > > > > > > > >> > > > > > > > 2) Can/should external (non-Kafka) tools have direct > access > > >> to > > >> > the > > >> > > > > > messages > > >> > > > > > > > in cold storage. I think this might have been addressed > > >> when > > >> > someone > > >> > > > > > asked > > >> > > > > > > > about ACLs, and I believe the answer is "no" -- if some > > >> > external tool > > >> > > > > > needs > > >> > > > > > > > to operate on that data then that external tool should > read > > >> > that data > > >> > > > > > by > > >> > > > > > > > acting as a Kafka consumer. Again, just asking to get > the > > >> > answer > > >> > > > > > clearly > > >> > > > > > > > documented in case it is unclear. > > >> > > > > > > > > > >> > > > > > > > Ron > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > On Thu, Apr 4, 2019 at 12:53 AM Harsha <ka...@harsha.io > > > > >> > wrote: > > >> > > > > > > > > > >> > > > > > > > > Hi Viktor, > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > "Now, will the consumer be able to consume a remote > > >> segment > > >> > if: > > >> > > > > > > > > - the remote segment is stored in the remote storage, > BUT > > >> > > > > > > > > - the leader broker failed right after this AND > > >> > > > > > > > > - the follower which is to become a leader didn't > scan yet > > >> > for a > > >> > > > > new > > >> > > > > > > > > segment?" > > >> > > > > > > > > > > >> > > > > > > > > If I understand correctly, after a local log segment > > >> copied > > >> > to > > >> > > > > > remote and > > >> > > > > > > > > leader is failed to write the index files and > leadership > > >> > changed > > >> > > > > to a > > >> > > > > > > > > follower. In this case we consider the log segment > copy > > >> > failed and > > >> > > > > > newly > > >> > > > > > > > > elected leader will start copying the data from last > the > > >> > known > > >> > > > > > offset in > > >> > > > > > > > > the remote to copy. Consumers who are looking for the > > >> > offset which > > >> > > > > > might > > >> > > > > > > > > be in the failed copy log segment will continue to be > read > > >> > the data > > >> > > > > > from > > >> > > > > > > > > local disk since the local log segment will only be > > >> deleted > > >> > once a > > >> > > > > > > > > successful copy of the log segment. > > >> > > > > > > > > > > >> > > > > > > > > "As a follow-up question, what are your experiences, > does > > >> a > > >> > > > > failover > > >> > > > > > in a > > >> > > > > > > > > broker causes bigger than usual churn in the > consumers? > > >> (I'm > > >> > > > > > thinking about > > >> > > > > > > > > the time required to rebuild remote index files.)" > > >> > > > > > > > > > > >> > > > > > > > > Rebuild remote index files will only happen in case of > > >> > remote > > >> > > > > > storage > > >> > > > > > > > > missing all the copied index files. Fail-over will > not > > >> > trigger > > >> > > > > this > > >> > > > > > > > > rebuild. > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > Hi Ryan, > > >> > > > > > > > > > > >> > > > > > > > > "Harsha, can you comment on this alternative approach: > > >> > instead of > > >> > > > > > fetching > > >> > > > > > > > > directly from remote storage via a new API, implement > > >> > something > > >> > > > > like > > >> > > > > > > > > paging, where segments are paged-in and out of cold > > >> storage > > >> > based > > >> > > > > on > > >> > > > > > access > > >> > > > > > > > > frequency/recency? For example, when a remote segment > is > > >> > accessed, > > >> > > > > > it could > > >> > > > > > > > > be first fetched to disk and then read from there. I > > >> suppose > > >> > this > > >> > > > > > would > > >> > > > > > > > > require less code changes, or at least less API > changes." > > >> > > > > > > > > > > >> > > > > > > > > Copying whole log segment from remote is inefficient. > When > > >> > tiered > > >> > > > > > storage > > >> > > > > > > > > is enabled users might prefer hardware with smaller > disks > > >> and > > >> > > > > having > > >> > > > > > to > > >> > > > > > > > > copy the log segment to local disk again , especially > > >> incase > > >> > of > > >> > > > > > multiple > > >> > > > > > > > > consumers on multiple topics triggering this might > > >> negatively > > >> > > > > affect > > >> > > > > > the > > >> > > > > > > > > available local storage. > > >> > > > > > > > > What we proposed in the KIP doesn't affect the > existing > > >> APIs > > >> > and we > > >> > > > > > didn't > > >> > > > > > > > > call for any API changes. > > >> > > > > > > > > > > >> > > > > > > > > "And related to paging, does the proposal address what > > >> > happens > > >> > > > > when a > > >> > > > > > > > > broker > > >> > > > > > > > > runs out of HDD space? Maybe we should have a way to > > >> > configure a > > >> > > > > max > > >> > > > > > number > > >> > > > > > > > > of segments or bytes stored on each broker, after > which > > >> > older or > > >> > > > > > > > > least-recently-used segments are kicked out, even if > they > > >> > aren't > > >> > > > > > expired > > >> > > > > > > > > per the retention policy? Otherwise, I suppose tiered > > >> storage > > >> > > > > > requires some > > >> > > > > > > > > babysitting to ensure that brokers don't run out of > local > > >> > storage, > > >> > > > > > despite > > >> > > > > > > > > having access to potentially unbounded cold storage." > > >> > > > > > > > > > > >> > > > > > > > > Existing Kafka behavior will not change with addition > of > > >> > tiered > > >> > > > > > storage > > >> > > > > > > > > and enabling it also will not change behavior. > > >> > > > > > > > > Just like today it's up to the operator to make sure > the > > >> HD > > >> > space > > >> > > > > is > > >> > > > > > > > > monitored and take necessary actions to mitigate that > > >> before > > >> > it > > >> > > > > > becomes > > >> > > > > > > > > fatal failure for broker. We don't stop users to > configure > > >> > the > > >> > > > > > retention > > >> > > > > > > > > period to infinite and they can easily run out of the > > >> space. > > >> > > > > > > > > > > >> > > > > > > > > These are not the alternatives considered as they are > not > > >> > efficient > > >> > > > > > copy > > >> > > > > > > > > in out of local disk , hence the reason we didn't add > to > > >> > > > > alternatives > > >> > > > > > > > > considered :). > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > Thanks, > > >> > > > > > > > > Harsha > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > On Wed, Apr 3, 2019, at 7:51 AM, Ryanne Dolan wrote: > > >> > > > > > > > > > Harsha, can you comment on this alternative > approach: > > >> > instead of > > >> > > > > > fetching > > >> > > > > > > > > > directly from remote storage via a new API, > implement > > >> > something > > >> > > > > > like > > >> > > > > > > > > > paging, where segments are paged-in and out of cold > > >> > storage based > > >> > > > > > on > > >> > > > > > > > > access > > >> > > > > > > > > > frequency/recency? For example, when a remote > segment is > > >> > > > > accessed, > > >> > > > > > it > > >> > > > > > > > > could > > >> > > > > > > > > > be first fetched to disk and then read from there. I > > >> > suppose this > > >> > > > > > would > > >> > > > > > > > > > require less code changes, or at least less API > changes. > > >> > > > > > > > > > > > >> > > > > > > > > > And related to paging, does the proposal address > what > > >> > happens > > >> > > > > when > > >> > > > > > a > > >> > > > > > > > > broker > > >> > > > > > > > > > runs out of HDD space? Maybe we should have a way to > > >> > configure a > > >> > > > > > max > > >> > > > > > > > > number > > >> > > > > > > > > > of segments or bytes stored on each broker, after > which > > >> > older or > > >> > > > > > > > > > least-recently-used segments are kicked out, even if > > >> they > > >> > aren't > > >> > > > > > expired > > >> > > > > > > > > > per the retention policy? Otherwise, I suppose > tiered > > >> > storage > > >> > > > > > requires > > >> > > > > > > > > some > > >> > > > > > > > > > babysitting to ensure that brokers don't run out of > > >> local > > >> > > > > storage, > > >> > > > > > > > > despite > > >> > > > > > > > > > having access to potentially unbounded cold storage. > > >> > > > > > > > > > > > >> > > > > > > > > > Just some things to add to Alternatives Considered > :) > > >> > > > > > > > > > > > >> > > > > > > > > > Ryanne > > >> > > > > > > > > > > > >> > > > > > > > > > On Wed, Apr 3, 2019 at 8:21 AM Viktor Somogyi-Vass < > > >> > > > > > > > > viktorsomo...@gmail.com> > > >> > > > > > > > > > wrote: > > >> > > > > > > > > > > > >> > > > > > > > > > > Hi Harsha, > > >> > > > > > > > > > > > > >> > > > > > > > > > > Thanks for the answer, makes sense. > > >> > > > > > > > > > > In the meantime one edge case popped up in my > mind but > > >> > first > > >> > > > > let > > >> > > > > > me > > >> > > > > > > > > > > summarize what I understand if I interpret your > KIP > > >> > correctly. > > >> > > > > > > > > > > > > >> > > > > > > > > > > So basically whenever the leader RSM copies over a > > >> > segment to > > >> > > > > the > > >> > > > > > > > > remote > > >> > > > > > > > > > > storage, the leader RLM will append an entry to > its > > >> > remote > > >> > > > > index > > >> > > > > > files > > >> > > > > > > > > with > > >> > > > > > > > > > > the remote position. After this LogManager can > delete > > >> > the local > > >> > > > > > > > > segment. > > >> > > > > > > > > > > Parallel to this RLM followers are periodically > > >> scanning > > >> > the > > >> > > > > > remote > > >> > > > > > > > > storage > > >> > > > > > > > > > > for files and if they find a new one they update > their > > >> > indices. > > >> > > > > > > > > > > > > >> > > > > > > > > > > Now, will the consumer be able to consume a remote > > >> > segment if: > > >> > > > > > > > > > > - the remote segment is stored in the remote > storage, > > >> BUT > > >> > > > > > > > > > > - the leader broker failed right after this AND > > >> > > > > > > > > > > - the follower which is to become a leader didn't > scan > > >> > yet for > > >> > > > > a > > >> > > > > > new > > >> > > > > > > > > > > segment? > > >> > > > > > > > > > > Would this result in an OffsetOutOfRangeException > or > > >> > would the > > >> > > > > > failover > > >> > > > > > > > > > > halt the consume request until the new leader has > the > > >> > latest > > >> > > > > > > > > information? > > >> > > > > > > > > > > As a follow-up question, what are your > experiences, > > >> does > > >> > a > > >> > > > > > failover in > > >> > > > > > > > > a > > >> > > > > > > > > > > broker causes bigger than usual churn in the > > >> consumers? > > >> > (I'm > > >> > > > > > thinking > > >> > > > > > > > > about > > >> > > > > > > > > > > the time required to rebuild remote index files.) > > >> > > > > > > > > > > > > >> > > > > > > > > > > Thanks, > > >> > > > > > > > > > > Viktor > > >> > > > > > > > > > > > > >> > > > > > > > > > > On Mon, Apr 1, 2019 at 8:49 PM Harsha < > > >> ka...@harsha.io> > > >> > wrote: > > >> > > > > > > > > > > > > >> > > > > > > > > > > > Hi Eno, > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Thanks for the comments. Answers are > inline > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "Performance & durability > > >> > > > > > > > > > > > ---------------------------------- > > >> > > > > > > > > > > > - would be good to have more discussion on > > >> performance > > >> > > > > > implications > > >> > > > > > > > > of > > >> > > > > > > > > > > > tiering. Copying the data from the local > storage to > > >> the > > >> > > > > remote > > >> > > > > > > > > storage is > > >> > > > > > > > > > > > going to be expensive in terms of network > bandwidth > > >> > and will > > >> > > > > > affect > > >> > > > > > > > > > > > foreground traffic to Kafka potentially > reducing its > > >> > > > > > throughput and > > >> > > > > > > > > > > > latency." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Good point. We've run our local tests with > 10GigE > > >> > cards, even > > >> > > > > > though > > >> > > > > > > > > our > > >> > > > > > > > > > > > clients bandwidth requirements are high with > 1000s > > >> of > > >> > clients > > >> > > > > > > > > producing / > > >> > > > > > > > > > > > consuming data we never hit hit our limits on > > >> network > > >> > > > > > bandwidth. More > > >> > > > > > > > > > > often > > >> > > > > > > > > > > > we hit limits of CPU, Mem limits than the > network > > >> > bandwidth. > > >> > > > > > But > > >> > > > > > > > > this is > > >> > > > > > > > > > > > something to be taken care of by the operator if > > >> they > > >> > want to > > >> > > > > > enable > > >> > > > > > > > > > > tiered > > >> > > > > > > > > > > > storage. > > >> > > > > > > > > > > > Also as mentioned in the KIP/previous threads > > >> ,clients > > >> > > > > > requesting > > >> > > > > > > > > older > > >> > > > > > > > > > > > data is very rare and often used as insurance > > >> policy . > > >> > What > > >> > > > > > proposed > > >> > > > > > > > > here > > >> > > > > > > > > > > > does increase bandwidth interms of shipping > > >> > logsegments to > > >> > > > > > remote but > > >> > > > > > > > > > > > access patterns determines how much we end up > > >> reading > > >> > from > > >> > > > > > remote > > >> > > > > > > > > tier. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "- throttling the copying of the data above > might > > >> be a > > >> > > > > > solution, > > >> > > > > > > > > however, > > >> > > > > > > > > > > > if > > >> > > > > > > > > > > > you have a few TB of data to move to the slower > > >> remote > > >> > tier > > >> > > > > > the risk > > >> > > > > > > > > is > > >> > > > > > > > > > > > that the movement will never complete on time > under > > >> > high > > >> > > > > Kafka > > >> > > > > > load. > > >> > > > > > > > > Do > > >> > > > > > > > > > > we > > >> > > > > > > > > > > > need a scheduler to use idle time to do the > > >> copying?" > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > In our design, we are going to have scheduler > in RLM > > >> > which > > >> > > > > will > > >> > > > > > > > > > > > periodically copy in-active(rolled-over) log > > >> segments. > > >> > > > > > > > > > > > Not sure idle time is easy to calculate and > > >> schedule a > > >> > copy. > > >> > > > > > More > > >> > > > > > > > > over we > > >> > > > > > > > > > > > want to copy the segments as soon as they are > > >> > available. > > >> > > > > > > > > > > > Throttling something we can take into account > and > > >> > provide > > >> > > > > > options to > > >> > > > > > > > > tune > > >> > > > > > > > > > > > it. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "- Have you considered having two options: 1) a > slow > > >> > tier > > >> > > > > only > > >> > > > > > > > > (e.g., all > > >> > > > > > > > > > > > the data on HDFS) and 2) a fast tier only like > Kafka > > >> > today. > > >> > > > > > This > > >> > > > > > > > > would > > >> > > > > > > > > > > > avoid copying data between the tiers. Customers > that > > >> > can > > >> > > > > > tolerate a > > >> > > > > > > > > > > slower > > >> > > > > > > > > > > > tier with a better price/GB can just choose > option > > >> > (1). Would > > >> > > > > > be > > >> > > > > > > > > good to > > >> > > > > > > > > > > > put in Alternatives considered." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > What we want to have is Kafka that is known to > the > > >> > users > > >> > > > > > today with > > >> > > > > > > > > > > local > > >> > > > > > > > > > > > fast disk access and fast data serving layer. > > >> Tiered > > >> > Storage > > >> > > > > > option > > >> > > > > > > > > > > might > > >> > > > > > > > > > > > not be for everyone and most users who are happy > > >> with > > >> > Kafka > > >> > > > > > today > > >> > > > > > > > > > > shouldn't > > >> > > > > > > > > > > > see changes to their operation because of this > KIP. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Fundamentally, we believe remote tiered storage > data > > >> > accessed > > >> > > > > > very > > >> > > > > > > > > > > > infrequently. We expect anyone going to read > from > > >> > remote > > >> > > > > tiered > > >> > > > > > > > > storage > > >> > > > > > > > > > > > expects a slower read response (mostly > backfills). > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Making an explicit change like slow/fast tier > will > > >> > only cause > > >> > > > > > more > > >> > > > > > > > > > > > confusion and operation complexity that will > bring > > >> > into play. > > >> > > > > > With > > >> > > > > > > > > tiered > > >> > > > > > > > > > > > storage , only users who want to use cheaper > > >> long-term > > >> > > > > storage > > >> > > > > > can > > >> > > > > > > > > enable > > >> > > > > > > > > > > > it and others can operate the Kafka as its > today. > > >> It > > >> > will > > >> > > > > > give a > > >> > > > > > > > > good > > >> > > > > > > > > > > > balance of serving latest reads from local disk > > >> almost > > >> > all > > >> > > > > the > > >> > > > > > time > > >> > > > > > > > > and > > >> > > > > > > > > > > > shipping older data and reading from remote tier > > >> when > > >> > clients > > >> > > > > > needs > > >> > > > > > > > > the > > >> > > > > > > > > > > > older data. If necessary, we can re-visit > > >> > slow/fast-tier > > >> > > > > > options at a > > >> > > > > > > > > > > later > > >> > > > > > > > > > > > point. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "Topic configs > > >> > > > > > > > > > > > ------------------ > > >> > > > > > > > > > > > - related to performance but also availability, > we > > >> > need to > > >> > > > > > discuss > > >> > > > > > > > > the > > >> > > > > > > > > > > > replication mode for the remote tier. For > example, > > >> if > > >> > the > > >> > > > > Kafka > > >> > > > > > > > > topics > > >> > > > > > > > > > > used > > >> > > > > > > > > > > > to have 3-way replication, will they continue to > > >> have > > >> > 3-way > > >> > > > > > > > > replication > > >> > > > > > > > > > > on > > >> > > > > > > > > > > > the remote tier? Will the user configure that > > >> > replication? In > > >> > > > > > S3 for > > >> > > > > > > > > > > > example, one can choose from different S3 tiers > like > > >> > STD or > > >> > > > > > SIA, but > > >> > > > > > > > > > > there > > >> > > > > > > > > > > > is no direct control over the replication factor > > >> like > > >> > in > > >> > > > > > Kafka." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > No. Remote tier is expected to be reliable > storage > > >> > with its > > >> > > > > own > > >> > > > > > > > > > > > replication mechanisms. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > " how will security and ACLs be configured for > the > > >> > remote > > >> > > > > tier. > > >> > > > > > > > > E.g., if > > >> > > > > > > > > > > > user A does not have access to a Kafka topic, > when > > >> > that topic > > >> > > > > > is > > >> > > > > > > > > moved to > > >> > > > > > > > > > > > S3 or HDFS there needs to be a way to prevent > access > > >> > to the > > >> > > > > S3 > > >> > > > > > > > > bucket for > > >> > > > > > > > > > > > that user. This might be outside the scope of > this > > >> KIP > > >> > but > > >> > > > > > would be > > >> > > > > > > > > good > > >> > > > > > > > > > > to > > >> > > > > > > > > > > > discuss first." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > As mentioned in the KIP "Alternatives" section > We > > >> > will keep > > >> > > > > > the > > >> > > > > > > > > Kafka as > > >> > > > > > > > > > > > the owner of those files in S3 or HDFS and take > > >> > advantage of > > >> > > > > > HDFS > > >> > > > > > > > > > > security > > >> > > > > > > > > > > > model (file system permissions). So any user who > > >> wants > > >> > to go > > >> > > > > > > > > directly and > > >> > > > > > > > > > > > access files from HDFS will not be able to read > them > > >> > and any > > >> > > > > > client > > >> > > > > > > > > > > > requests will go through Kafka and its ACLs will > > >> apply > > >> > like > > >> > > > > it > > >> > > > > > does > > >> > > > > > > > > for > > >> > > > > > > > > > > any > > >> > > > > > > > > > > > other request. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Hi Ron, > > >> > > > > > > > > > > > Thanks for the comments. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > " I'm excited about this potential feature. > Did you > > >> > consider > > >> > > > > > > > > > > > storing the information about the remote > segments > > >> in a > > >> > Kafka > > >> > > > > > topic as > > >> > > > > > > > > > > > opposed to in the remote storage itself? The > topic > > >> > would > > >> > > > > need > > >> > > > > > > > > infinite > > >> > > > > > > > > > > > retention (or it would need to be compacted) so > as > > >> not > > >> > to > > >> > > > > > itself be > > >> > > > > > > > > sent > > >> > > > > > > > > > > to > > >> > > > > > > > > > > > cold storage, but assuming that topic would fit > on > > >> > local disk > > >> > > > > > for all > > >> > > > > > > > > > > time > > >> > > > > > > > > > > > (an open question as to whether this is > acceptable > > >> or > > >> > not) it > > >> > > > > > feels > > >> > > > > > > > > like > > >> > > > > > > > > > > > the most natural way to communicate information > > >> among > > >> > brokers > > >> > > > > > -- more > > >> > > > > > > > > > > > natural than having them poll the remote storage > > >> > systems, at > > >> > > > > > least." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > With RemoteIndex we are extending the current > index > > >> > mechanism > > >> > > > > > to > > >> > > > > > > > > find a > > >> > > > > > > > > > > > offset and its message to find a file in remote > > >> > storage for a > > >> > > > > > givent > > >> > > > > > > > > > > > offset. This will be optimal way finding for a > given > > >> > offset > > >> > > > > > which > > >> > > > > > > > > remote > > >> > > > > > > > > > > > segment might be serving compare to storing all > of > > >> > this data > > >> > > > > > into > > >> > > > > > > > > > > internal > > >> > > > > > > > > > > > topic. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "To add to Eric's question/confusion about where > > >> logic > > >> > lives > > >> > > > > > (RLM vs. > > >> > > > > > > > > > > RSM), > > >> > > > > > > > > > > > I think it would be helpful to explicitly > identify > > >> in > > >> > the KIP > > >> > > > > > that > > >> > > > > > > > > the > > >> > > > > > > > > > > RLM > > >> > > > > > > > > > > > delegates to the RSM since the RSM is part of > the > > >> > public API > > >> > > > > > and is > > >> > > > > > > > > the > > >> > > > > > > > > > > > pluggable piece. For example, instead of saying > > >> "RLM > > >> > will > > >> > > > > > ship the > > >> > > > > > > > > log > > >> > > > > > > > > > > > segment files that are older than a configurable > > >> time > > >> > to > > >> > > > > remote > > >> > > > > > > > > storage" > > >> > > > > > > > > > > I > > >> > > > > > > > > > > > think it would be better to say "RLM identifies > log > > >> > segment > > >> > > > > > files > > >> > > > > > > > > that > > >> > > > > > > > > > > are > > >> > > > > > > > > > > > older than a configurable time and delegates to > the > > >> > > > > configured > > >> > > > > > RSM to > > >> > > > > > > > > > > ship > > >> > > > > > > > > > > > them to remote storage" (or something like that > -- > > >> > just make > > >> > > > > > it clear > > >> > > > > > > > > > > that > > >> > > > > > > > > > > > the RLM is delegating to the configured RSM)." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Thanks. I agree with you. I'll update the KIP. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Hi Ambud, > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Thanks for the comments. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "1. Wouldn't implicit checking for old offsets > in > > >> > remote > > >> > > > > > location if > > >> > > > > > > > > not > > >> > > > > > > > > > > > found locally on the leader i.e. do we really > need > > >> > remote > > >> > > > > index > > >> > > > > > > > > files? > > >> > > > > > > > > > > > Since the storage path for a given topic would > > >> > presumably be > > >> > > > > > constant > > >> > > > > > > > > > > > across all the brokers, the remote > topic-partition > > >> > path could > > >> > > > > > simply > > >> > > > > > > > > be > > >> > > > > > > > > > > > checked to see if there are any segment file > names > > >> > that would > > >> > > > > > meet > > >> > > > > > > > > the > > >> > > > > > > > > > > > offset requirements for a Consumer Fetch > Request. > > >> RSM > > >> > > > > > implementations > > >> > > > > > > > > > > could > > >> > > > > > > > > > > > optionally cache this information." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > By storing the remote index files locally , it > will > > >> be > > >> > faster > > >> > > > > > for us > > >> > > > > > > > > to > > >> > > > > > > > > > > > determine for a requested offset which file > might > > >> > contain the > > >> > > > > > data. > > >> > > > > > > > > This > > >> > > > > > > > > > > > will help us resolve the remote file quickly and > > >> > return the > > >> > > > > > response. > > >> > > > > > > > > > > > Instead of making a call to remote tier for > index > > >> look > > >> > up. > > >> > > > > > Given > > >> > > > > > > > > index > > >> > > > > > > > > > > > files are smaller , it won't be much hit to the > > >> storage > > >> > > > > space. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "2. Would it make sense to create an internal > > >> > compacted Kafka > > >> > > > > > topic > > >> > > > > > > > > to > > >> > > > > > > > > > > > publish & record remote segment information? > This > > >> would > > >> > > > > enable > > >> > > > > > the > > >> > > > > > > > > > > > followers to get updates about new segments > rather > > >> than > > >> > > > > running > > >> > > > > > > > > list() > > >> > > > > > > > > > > > operations on remote storage to detect new > segments > > >> > which may > > >> > > > > > be > > >> > > > > > > > > > > > expensive." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > I think Ron also alluding to this. We thought > > >> shipping > > >> > remote > > >> > > > > > index > > >> > > > > > > > > files > > >> > > > > > > > > > > > to remote storage files and let the follower's > RLM > > >> > picking > > >> > > > > > that up > > >> > > > > > > > > makes > > >> > > > > > > > > > > it > > >> > > > > > > > > > > > easy to have the current replication protocol > > >> without > > >> > any > > >> > > > > > changes. > > >> > > > > > > > > So we > > >> > > > > > > > > > > > don't determine if a follower is in ISR or not > > >> based on > > >> > > > > another > > >> > > > > > > > > topic's > > >> > > > > > > > > > > > replication. We will run small tests and > determine > > >> if > > >> > use of > > >> > > > > > topic > > >> > > > > > > > > is > > >> > > > > > > > > > > > better for this. Thanks for the suggestion. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > 3. For RLM to scan local segment rotations are > you > > >> > thinking > > >> > > > > of > > >> > > > > > > > > leveraging > > >> > > > > > > > > > > > java.nio.file.WatchService or simply running > > >> > listFiles() on a > > >> > > > > > > > > periodic > > >> > > > > > > > > > > > basis? Since WatchService implementation is > heavily > > >> OS > > >> > > > > > dependent it > > >> > > > > > > > > might > > >> > > > > > > > > > > > create some complications around missing FS > Events. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Ideally we want to introduce file events like > you > > >> > suggested. > > >> > > > > > For POC > > >> > > > > > > > > work > > >> > > > > > > > > > > > we are using just listFiles(). Also copying > these > > >> > files to > > >> > > > > > remote > > >> > > > > > > > > can be > > >> > > > > > > > > > > > slower and we will not delete the files from > local > > >> > disk until > > >> > > > > > the > > >> > > > > > > > > segment > > >> > > > > > > > > > > > is copied and any requests to the data in these > > >> files > > >> > will be > > >> > > > > > served > > >> > > > > > > > > from > > >> > > > > > > > > > > > local disk. So I don't think we need to be > > >> aggressive > > >> > and > > >> > > > > > optimize > > >> > > > > > > > > the > > >> > > > > > > > > > > this > > >> > > > > > > > > > > > copy segment to remote path. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Hi Viktor, > > >> > > > > > > > > > > > Thanks for the comments. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > "I have a rather technical question to this. > How do > > >> > you plan > > >> > > > > to > > >> > > > > > > > > package > > >> > > > > > > > > > > > this > > >> > > > > > > > > > > > extension? Does this mean that Kafka will > depend on > > >> > HDFS? > > >> > > > > > > > > > > > I think it'd be nice to somehow separate this > off > > >> to a > > >> > > > > > different > > >> > > > > > > > > package > > >> > > > > > > > > > > in > > >> > > > > > > > > > > > the project so that it could be built and > released > > >> > separately > > >> > > > > > from > > >> > > > > > > > > the > > >> > > > > > > > > > > main > > >> > > > > > > > > > > > Kafka packages." > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > We would like all of this code to be part of > Apache > > >> > Kafka . > > >> > > > > In > > >> > > > > > early > > >> > > > > > > > > days > > >> > > > > > > > > > > > of Kafka, there is external module which used to > > >> > contain > > >> > > > > kafka > > >> > > > > > to > > >> > > > > > > > > hdfs > > >> > > > > > > > > > > copy > > >> > > > > > > > > > > > tools and dependencies. We would like to have > RLM > > >> > (class > > >> > > > > > > > > implementation) > > >> > > > > > > > > > > > and RSM(interface) to be in core and as you > > >> suggested, > > >> > > > > > > > > implementation of > > >> > > > > > > > > > > > RSM could be in another package so that the > > >> > dependencies of > > >> > > > > > RSM won't > > >> > > > > > > > > > > come > > >> > > > > > > > > > > > into Kafka's classpath unless someone explicity > > >> > configures > > >> > > > > > them. > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > Harsha > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > On Mon, Apr 1, 2019, at 1:02 AM, Viktor > Somogyi-Vass > > >> > wrote: > > >> > > > > > > > > > > > > Hey Harsha, > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > I have a rather technical question to this. > How do > > >> > you plan > > >> > > > > > to > > >> > > > > > > > > package > > >> > > > > > > > > > > > this > > >> > > > > > > > > > > > > extension? Does this mean that Kafka will > depend > > >> on > > >> > HDFS? > > >> > > > > > > > > > > > > I think it'd be nice to somehow separate this > off > > >> to > > >> > a > > >> > > > > > different > > >> > > > > > > > > > > package > > >> > > > > > > > > > > > in > > >> > > > > > > > > > > > > the project so that it could be built and > released > > >> > > > > > separately from > > >> > > > > > > > > the > > >> > > > > > > > > > > > main > > >> > > > > > > > > > > > > Kafka packages. > > >> > > > > > > > > > > > > This decoupling would be useful when direct > > >> > dependency on > > >> > > > > > HDFS (or > > >> > > > > > > > > > > other > > >> > > > > > > > > > > > > implementations) is not needed and would also > > >> > encourage > > >> > > > > > decoupling > > >> > > > > > > > > for > > >> > > > > > > > > > > > > other storage implementations. > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > Best, > > >> > > > > > > > > > > > > Viktor > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > On Mon, Apr 1, 2019 at 3:44 AM Ambud Sharma < > > >> > > > > > > > > asharma52...@gmail.com> > > >> > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > Hi Harsha, > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > Thank you for proposing this KIP. We are > looking > > >> > forward > > >> > > > > > to this > > >> > > > > > > > > > > > feature as > > >> > > > > > > > > > > > > > well. > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > A few questions around the design & > > >> implementation: > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > 1. Wouldn't implicit checking for old > offsets in > > >> > remote > > >> > > > > > location > > >> > > > > > > > > if > > >> > > > > > > > > > > not > > >> > > > > > > > > > > > > > found locally on the leader i.e. do we > really > > >> need > > >> > remote > > >> > > > > > index > > >> > > > > > > > > > > files? > > >> > > > > > > > > > > > > > Since the storage path for a given topic > would > > >> > presumably > > >> > > > > > be > > >> > > > > > > > > constant > > >> > > > > > > > > > > > > > across all the brokers, the remote > > >> topic-partition > > >> > path > > >> > > > > > could > > >> > > > > > > > > simply > > >> > > > > > > > > > > be > > >> > > > > > > > > > > > > > checked to see if there are any segment file > > >> names > > >> > that > > >> > > > > > would > > >> > > > > > > > > meet > > >> > > > > > > > > > > the > > >> > > > > > > > > > > > > > offset requirements for a Consumer Fetch > > >> Request. > > >> > RSM > > >> > > > > > > > > implementations > > >> > > > > > > > > > > > could > > >> > > > > > > > > > > > > > optionally cache this information. > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > 2. Would it make sense to create an internal > > >> > compacted > > >> > > > > > Kafka > > >> > > > > > > > > topic to > > >> > > > > > > > > > > > > > publish & record remote segment information? > > >> This > > >> > would > > >> > > > > > enable > > >> > > > > > > > > the > > >> > > > > > > > > > > > > > followers to get updates about new segments > > >> rather > > >> > than > > >> > > > > > running > > >> > > > > > > > > > > list() > > >> > > > > > > > > > > > > > operations on remote storage to detect new > > >> > segments which > > >> > > > > > may be > > >> > > > > > > > > > > > expensive. > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > 3. For RLM to scan local segment rotations > are > > >> you > > >> > > > > > thinking of > > >> > > > > > > > > > > > leveraging > > >> > > > > > > > > > > > > > java.nio.file.WatchService or simply running > > >> > listFiles() > > >> > > > > > on a > > >> > > > > > > > > > > periodic > > >> > > > > > > > > > > > > > basis? Since WatchService implementation is > > >> > heavily OS > > >> > > > > > dependent > > >> > > > > > > > > it > > >> > > > > > > > > > > > might > > >> > > > > > > > > > > > > > create some complications around missing FS > > >> Events. > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > Thanks. > > >> > > > > > > > > > > > > > Ambud > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > On Thu, Mar 28, 2019 at 8:04 AM Ron > Dagostino < > > >> > > > > > rndg...@gmail.com > > >> > > > > > > > > > > > >> > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > Hi Harsha. I'm excited about this > potential > > >> > feature. > > >> > > > > > Did you > > >> > > > > > > > > > > > consider > > >> > > > > > > > > > > > > > > storing the information about the remote > > >> > segments in a > > >> > > > > > Kafka > > >> > > > > > > > > topic > > >> > > > > > > > > > > as > > >> > > > > > > > > > > > > > > opposed to in the remote storage itself? > The > > >> > topic > > >> > > > > > would need > > >> > > > > > > > > > > > infinite > > >> > > > > > > > > > > > > > > retention (or it would need to be > compacted) > > >> so > > >> > as not > > >> > > > > to > > >> > > > > > > > > itself be > > >> > > > > > > > > > > > sent > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > cold storage, but assuming that topic > would > > >> fit > > >> > on > > >> > > > > local > > >> > > > > > disk > > >> > > > > > > > > for > > >> > > > > > > > > > > all > > >> > > > > > > > > > > > > > time > > >> > > > > > > > > > > > > > > (an open question as to whether this is > > >> > acceptable or > > >> > > > > > not) it > > >> > > > > > > > > feels > > >> > > > > > > > > > > > like > > >> > > > > > > > > > > > > > > the most natural way to communicate > > >> information > > >> > among > > >> > > > > > brokers > > >> > > > > > > > > -- > > >> > > > > > > > > > > more > > >> > > > > > > > > > > > > > > natural than having them poll the remote > > >> storage > > >> > > > > > systems, at > > >> > > > > > > > > least. > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > To add to Eric's question/confusion about > > >> where > > >> > logic > > >> > > > > > lives > > >> > > > > > > > > (RLM > > >> > > > > > > > > > > vs. > > >> > > > > > > > > > > > > > RSM), > > >> > > > > > > > > > > > > > > I think it would be helpful to explicitly > > >> > identify in > > >> > > > > > the KIP > > >> > > > > > > > > that > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > RLM > > >> > > > > > > > > > > > > > > delegates to the RSM since the RSM is > part of > > >> the > > >> > > > > public > > >> > > > > > API > > >> > > > > > > > > and is > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > pluggable piece. For example, instead of > > >> saying > > >> > "RLM > > >> > > > > > will > > >> > > > > > > > > ship the > > >> > > > > > > > > > > > log > > >> > > > > > > > > > > > > > > segment files that are older than a > > >> configurable > > >> > time > > >> > > > > to > > >> > > > > > remote > > >> > > > > > > > > > > > storage" > > >> > > > > > > > > > > > > > I > > >> > > > > > > > > > > > > > > think it would be better to say "RLM > > >> identifies > > >> > log > > >> > > > > > segment > > >> > > > > > > > > files > > >> > > > > > > > > > > > that > > >> > > > > > > > > > > > > > are > > >> > > > > > > > > > > > > > > older than a configurable time and > delegates > > >> to > > >> > the > > >> > > > > > configured > > >> > > > > > > > > RSM > > >> > > > > > > > > > > to > > >> > > > > > > > > > > > > > ship > > >> > > > > > > > > > > > > > > them to remote storage" (or something like > > >> that > > >> > -- just > > >> > > > > > make it > > >> > > > > > > > > > > clear > > >> > > > > > > > > > > > > > that > > >> > > > > > > > > > > > > > > the RLM is delegating to the configured > RSM). > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > Ron > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > On Thu, Mar 28, 2019 at 6:12 AM Eno > Thereska < > > >> > > > > > > > > > > eno.there...@gmail.com > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > Thanks Harsha, > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > A couple of comments: > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > Performance & durability > > >> > > > > > > > > > > > > > > > ---------------------------------- > > >> > > > > > > > > > > > > > > > - would be good to have more discussion > on > > >> > > > > performance > > >> > > > > > > > > > > > implications of > > >> > > > > > > > > > > > > > > > tiering. Copying the data from the local > > >> > storage to > > >> > > > > the > > >> > > > > > > > > remote > > >> > > > > > > > > > > > storage > > >> > > > > > > > > > > > > > is > > >> > > > > > > > > > > > > > > > going to be expensive in terms of > network > > >> > bandwidth > > >> > > > > > and will > > >> > > > > > > > > > > affect > > >> > > > > > > > > > > > > > > > foreground traffic to Kafka potentially > > >> > reducing its > > >> > > > > > > > > throughput > > >> > > > > > > > > > > and > > >> > > > > > > > > > > > > > > > latency. > > >> > > > > > > > > > > > > > > > - throttling the copying of the data > above > > >> > might be a > > >> > > > > > > > > solution, > > >> > > > > > > > > > > > however > > >> > > > > > > > > > > > > > > if > > >> > > > > > > > > > > > > > > > you have a few TB of data to move to the > > >> slower > > >> > > > > remote > > >> > > > > > tier > > >> > > > > > > > > the > > >> > > > > > > > > > > > risk is > > >> > > > > > > > > > > > > > > > that the movement will never complete on > > >> time > > >> > under > > >> > > > > > high > > >> > > > > > > > > Kafka > > >> > > > > > > > > > > > load. Do > > >> > > > > > > > > > > > > > > we > > >> > > > > > > > > > > > > > > > need a scheduler to use idle time to do > the > > >> > copying? > > >> > > > > > > > > > > > > > > > - Have you considered having two > options: > > >> 1) a > > >> > slow > > >> > > > > > tier only > > >> > > > > > > > > > > > (e.g., > > >> > > > > > > > > > > > > > all > > >> > > > > > > > > > > > > > > > the data on HDFS) and 2) a fast tier > only > > >> like > > >> > Kafka > > >> > > > > > today. > > >> > > > > > > > > This > > >> > > > > > > > > > > > would > > >> > > > > > > > > > > > > > > > avoid copying data between the tiers. > > >> > Customers that > > >> > > > > > can > > >> > > > > > > > > > > tolerate a > > >> > > > > > > > > > > > > > > slower > > >> > > > > > > > > > > > > > > > tier with a better price/GB can just > choose > > >> > option > > >> > > > > (1). > > >> > > > > > > > > Would be > > >> > > > > > > > > > > > good > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > put in Alternatives considered. > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > Topic configs > > >> > > > > > > > > > > > > > > > ------------------ > > >> > > > > > > > > > > > > > > > - related to performance but also > > >> > availability, we > > >> > > > > > need to > > >> > > > > > > > > > > discuss > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > replication mode for the remote tier. > For > > >> > example, if > > >> > > > > > the > > >> > > > > > > > > Kafka > > >> > > > > > > > > > > > topics > > >> > > > > > > > > > > > > > > used > > >> > > > > > > > > > > > > > > > to have 3-way replication, will they > > >> continue > > >> > to have > > >> > > > > > 3-way > > >> > > > > > > > > > > > replication > > >> > > > > > > > > > > > > > > on > > >> > > > > > > > > > > > > > > > the remote tier? Will the user configure > > >> that > > >> > > > > > replication? > > >> > > > > > > > > In S3 > > >> > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > > example, one can choose from different > S3 > > >> > tiers like > > >> > > > > > STD or > > >> > > > > > > > > SIA, > > >> > > > > > > > > > > > but > > >> > > > > > > > > > > > > > > there > > >> > > > > > > > > > > > > > > > is no direct control over the > replication > > >> > factor like > > >> > > > > > in > > >> > > > > > > > > Kafka. > > >> > > > > > > > > > > > > > > > - how will security and ACLs be > configured > > >> for > > >> > the > > >> > > > > > remote > > >> > > > > > > > > tier. > > >> > > > > > > > > > > > E.g., > > >> > > > > > > > > > > > > > if > > >> > > > > > > > > > > > > > > > user A does not have access to a Kafka > > >> topic, > > >> > when > > >> > > > > that > > >> > > > > > > > > topic is > > >> > > > > > > > > > > > moved > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > S3 or HDFS there needs to be a way to > > >> prevent > > >> > access > > >> > > > > > to the > > >> > > > > > > > > S3 > > >> > > > > > > > > > > > bucket > > >> > > > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > > that user. This might be outside the > scope > > >> of > > >> > this > > >> > > > > KIP > > >> > > > > > but > > >> > > > > > > > > would > > >> > > > > > > > > > > be > > >> > > > > > > > > > > > > > good > > >> > > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > discuss first. > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > That's it for now, thanks > > >> > > > > > > > > > > > > > > > Eno > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > On Wed, Mar 27, 2019 at 4:40 PM Harsha < > > >> > > > > > ka...@harsha.io> > > >> > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > Hi All, > > >> > > > > > > > > > > > > > > > > Thanks for your initial > > >> feedback. > > >> > We > > >> > > > > > updated the > > >> > > > > > > > > > > KIP. > > >> > > > > > > > > > > > > > Please > > >> > > > > > > > > > > > > > > > > take a look and let us know if you > have > > >> any > > >> > > > > > questions. > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > >> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-405%3A+Kafka+Tiered+Storage > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > > > > > > Harsha > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > On Wed, Feb 6, 2019, at 10:30 AM, > Harsha > > >> > wrote: > > >> > > > > > > > > > > > > > > > > > Thanks Eno, Adam & Satish for you > review > > >> > and > > >> > > > > > questions. > > >> > > > > > > > > I'll > > >> > > > > > > > > > > > > > address > > >> > > > > > > > > > > > > > > > > > these in KIP and update the thread > here. > > >> > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > > > > > > > Harsha > > >> > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > On Wed, Feb 6, 2019, at 7:09 AM, > Satish > > >> > Duggana > > >> > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > Thanks, Harsha for the KIP. It is > a > > >> good > > >> > start > > >> > > > > > for > > >> > > > > > > > > tiered > > >> > > > > > > > > > > > storage > > >> > > > > > > > > > > > > > > in > > >> > > > > > > > > > > > > > > > > > > Kafka. I have a few > > >> comments/questions. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > It may be good to have a > configuration > > >> > to keep > > >> > > > > > the > > >> > > > > > > > > number > > >> > > > > > > > > > > of > > >> > > > > > > > > > > > > > local > > >> > > > > > > > > > > > > > > > > > > segments instead of keeping only > the > > >> > active > > >> > > > > > segment. > > >> > > > > > > > > This > > >> > > > > > > > > > > > config > > >> > > > > > > > > > > > > > > can > > >> > > > > > > > > > > > > > > > > > > be exposed at cluster and topic > levels > > >> > with > > >> > > > > > default > > >> > > > > > > > > value > > >> > > > > > > > > > > as > > >> > > > > > > > > > > > 1. > > >> > > > > > > > > > > > > > In > > >> > > > > > > > > > > > > > > > > > > some use cases, few consumers may > lag > > >> > over one > > >> > > > > > > > > segment, it > > >> > > > > > > > > > > > will > > >> > > > > > > > > > > > > > be > > >> > > > > > > > > > > > > > > > > > > better to serve from local storage > > >> > instead of > > >> > > > > > remote > > >> > > > > > > > > > > storage. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > It may be better to keep > > >> > > > > > “remote.log.storage.enable” > > >> > > > > > > > > and > > >> > > > > > > > > > > > > > respective > > >> > > > > > > > > > > > > > > > > > > configuration at topic level along > > >> with > > >> > cluster > > >> > > > > > level. > > >> > > > > > > > > It > > >> > > > > > > > > > > > will be > > >> > > > > > > > > > > > > > > > > > > helpful in environments where few > > >> topics > > >> > are > > >> > > > > > configured > > >> > > > > > > > > > > with > > >> > > > > > > > > > > > > > > > > > > local-storage and other topics are > > >> > configured > > >> > > > > > with > > >> > > > > > > > > remote > > >> > > > > > > > > > > > > > storage. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > Each topic-partition leader > pushes its > > >> > log > > >> > > > > > segments > > >> > > > > > > > > with > > >> > > > > > > > > > > > > > respective > > >> > > > > > > > > > > > > > > > > > > index files to remote whenever > active > > >> > log rolls > > >> > > > > > over, > > >> > > > > > > > > it > > >> > > > > > > > > > > > updates > > >> > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > > > remote log index file for the > > >> respective > > >> > remote > > >> > > > > > log > > >> > > > > > > > > > > segment. > > >> > > > > > > > > > > > The > > >> > > > > > > > > > > > > > > > > > > second option is to add offset > index > > >> > files also > > >> > > > > > for > > >> > > > > > > > > each > > >> > > > > > > > > > > > segment. > > >> > > > > > > > > > > > > > > It > > >> > > > > > > > > > > > > > > > > > > can serve consumer fetch requests > for > > >> old > > >> > > > > > segments from > > >> > > > > > > > > > > > local log > > >> > > > > > > > > > > > > > > > > > > segment instead of serving > directly > > >> from > > >> > the > > >> > > > > > remote log > > >> > > > > > > > > > > > which may > > >> > > > > > > > > > > > > > > > > > > cause high latencies. There can be > > >> > different > > >> > > > > > > > > strategies in > > >> > > > > > > > > > > > when > > >> > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > > > remote segment is copied to a > local > > >> > segment. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > What is “ > > >> > > > > > remote.log.manager.scheduler.interval.ms” > > >> > > > > > > > > config > > >> > > > > > > > > > > > about? > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > How do followers sync > > >> > RemoteLogSegmentIndex > > >> > > > > > files? Do > > >> > > > > > > > > they > > >> > > > > > > > > > > > > > request > > >> > > > > > > > > > > > > > > > > > > from leader replica? This looks > to be > > >> > important > > >> > > > > > as the > > >> > > > > > > > > > > failed > > >> > > > > > > > > > > > > > over > > >> > > > > > > > > > > > > > > > > > > leader should have > > >> RemoteLogSegmentIndex > > >> > > > > updated > > >> > > > > > and > > >> > > > > > > > > ready > > >> > > > > > > > > > > to > > >> > > > > > > > > > > > > > avoid > > >> > > > > > > > > > > > > > > > > > > high latencies in serving old data > > >> > stored in > > >> > > > > > remote > > >> > > > > > > > > logs. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > > > > > > > > Satish. > > >> > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > On Tue, Feb 5, 2019 at 10:42 PM > Ryanne > > >> > Dolan < > > >> > > > > > > > > > > > > > > ryannedo...@gmail.com> > > >> > > > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > Thanks Harsha, makes sense. > > >> > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > Ryanne > > >> > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > On Mon, Feb 4, 2019 at 5:53 PM > > >> Harsha > > >> > > > > > Chintalapani < > > >> > > > > > > > > > > > > > > > ka...@harsha.io> > > >> > > > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > "I think you are saying that > this > > >> > enables > > >> > > > > > > > > additional > > >> > > > > > > > > > > > > > > (potentially > > >> > > > > > > > > > > > > > > > > cheaper) > > >> > > > > > > > > > > > > > > > > > > > > storage options without > > >> *requiring* > > >> > an > > >> > > > > > existing ETL > > >> > > > > > > > > > > > > > pipeline. “ > > >> > > > > > > > > > > > > > > > > > > > > Yes. > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > " But it's not really a > > >> replacement > > >> > for the > > >> > > > > > sort of > > >> > > > > > > > > > > > pipelines > > >> > > > > > > > > > > > > > > > > people build > > >> > > > > > > > > > > > > > > > > > > > > with Connect, Gobblin etc.” > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > It is not. But also making an > > >> > assumption > > >> > > > > that > > >> > > > > > > > > everyone > > >> > > > > > > > > > > > runs > > >> > > > > > > > > > > > > > > these > > >> > > > > > > > > > > > > > > > > > > > > pipelines for storing raw > Kafka > > >> data > > >> > into > > >> > > > > > HDFS or > > >> > > > > > > > > S3 is > > >> > > > > > > > > > > > also > > >> > > > > > > > > > > > > > > > wrong > > >> > > > > > > > > > > > > > > > > > > > > assumption. > > >> > > > > > > > > > > > > > > > > > > > > The aim of this KIP is to > provide > > >> > tiered > > >> > > > > > storage as > > >> > > > > > > > > > > whole > > >> > > > > > > > > > > > > > > package > > >> > > > > > > > > > > > > > > > > not > > >> > > > > > > > > > > > > > > > > > > > > asking users to ship the data > on > > >> > their own > > >> > > > > > using > > >> > > > > > > > > > > existing > > >> > > > > > > > > > > > > > ETL, > > >> > > > > > > > > > > > > > > > > which means > > >> > > > > > > > > > > > > > > > > > > > > running a consumer and > maintaining > > >> > those > > >> > > > > > pipelines. > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > " My point was that, if you > are > > >> > already > > >> > > > > > offloading > > >> > > > > > > > > > > > records in > > >> > > > > > > > > > > > > > > an > > >> > > > > > > > > > > > > > > > > ETL > > >> > > > > > > > > > > > > > > > > > > > > pipeline, why do you need a > new > > >> > pipeline > > >> > > > > > built > > >> > > > > > > > > into the > > >> > > > > > > > > > > > > > broker > > >> > > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > ship the > > >> > > > > > > > > > > > > > > > > > > > > same data to the same place?” > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > As you said its ETL pipeline, > > >> which > > >> > means > > >> > > > > > users of > > >> > > > > > > > > > > these > > >> > > > > > > > > > > > > > > > pipelines > > >> > > > > > > > > > > > > > > > > are > > >> > > > > > > > > > > > > > > > > > > > > reading the data from broker > and > > >> > > > > > transforming its > > >> > > > > > > > > state > > >> > > > > > > > > > > > and > > >> > > > > > > > > > > > > > > > > storing it > > >> > > > > > > > > > > > > > > > > > > > > somewhere. > > >> > > > > > > > > > > > > > > > > > > > > The point of this KIP is > store log > > >> > segments > > >> > > > > > as it > > >> > > > > > > > > is > > >> > > > > > > > > > > > without > > >> > > > > > > > > > > > > > > > > changing > > >> > > > > > > > > > > > > > > > > > > > > their structure so that we > can use > > >> > the > > >> > > > > > existing > > >> > > > > > > > > offset > > >> > > > > > > > > > > > > > > mechanisms > > >> > > > > > > > > > > > > > > > > to look > > >> > > > > > > > > > > > > > > > > > > > > it up when the consumer needs > to > > >> > read old > > >> > > > > > data. > > >> > > > > > > > > When > > >> > > > > > > > > > > you > > >> > > > > > > > > > > > do > > >> > > > > > > > > > > > > > > load > > >> > > > > > > > > > > > > > > > > it via > > >> > > > > > > > > > > > > > > > > > > > > your existing pipelines you > are > > >> > reading the > > >> > > > > > topic > > >> > > > > > > > > as a > > >> > > > > > > > > > > > whole > > >> > > > > > > > > > > > > > , > > >> > > > > > > > > > > > > > > > > which > > >> > > > > > > > > > > > > > > > > > > > > doesn’t guarantee that you’ll > > >> > produce this > > >> > > > > > data > > >> > > > > > > > > back > > >> > > > > > > > > > > into > > >> > > > > > > > > > > > > > HDFS > > >> > > > > > > > > > > > > > > in > > >> > > > > > > > > > > > > > > > > S3 in the > > >> > > > > > > > > > > > > > > > > > > > > same order and who is going to > > >> > generate the > > >> > > > > > Index > > >> > > > > > > > > files > > >> > > > > > > > > > > > > > again. > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > "So you'd end up with one of > > >> 1)cold > > >> > > > > segments > > >> > > > > > are > > >> > > > > > > > > only > > >> > > > > > > > > > > > useful > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > Kafka; 2) > > >> > > > > > > > > > > > > > > > > > > > > you have the same data > written to > > >> > HDFS/etc > > >> > > > > > twice, > > >> > > > > > > > > once > > >> > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > and once > > >> > > > > > > > > > > > > > > > > > > > > for everything else, in two > > >> separate > > >> > > > > formats” > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > You are talking two different > use > > >> > cases. If > > >> > > > > > > > > someone is > > >> > > > > > > > > > > > > > storing > > >> > > > > > > > > > > > > > > > raw > > >> > > > > > > > > > > > > > > > > data > > >> > > > > > > > > > > > > > > > > > > > > out of Kafka for long term > access. > > >> > > > > > > > > > > > > > > > > > > > > By storing the data as it is > in > > >> HDFS > > >> > though > > >> > > > > > Kafka > > >> > > > > > > > > will > > >> > > > > > > > > > > > solve > > >> > > > > > > > > > > > > > > this > > >> > > > > > > > > > > > > > > > > issue. > > >> > > > > > > > > > > > > > > > > > > > > They do not need to run > another > > >> > pipe-line > > >> > > > > to > > >> > > > > > ship > > >> > > > > > > > > these > > >> > > > > > > > > > > > logs. > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > If they are running pipelines > to > > >> > store in > > >> > > > > > HDFS in a > > >> > > > > > > > > > > > different > > >> > > > > > > > > > > > > > > > > format, > > >> > > > > > > > > > > > > > > > > > > > > thats a different use case. > May be > > >> > they are > > >> > > > > > > > > > > transforming > > >> > > > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > logs to ORC > > >> > > > > > > > > > > > > > > > > > > > > so that they can query through > > >> > Hive. Once > > >> > > > > > you > > >> > > > > > > > > > > transform > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > log > > >> > > > > > > > > > > > > > > > > segment it > > >> > > > > > > > > > > > > > > > > > > > > does loose its ability to use > the > > >> > existing > > >> > > > > > offset > > >> > > > > > > > > > > index. > > >> > > > > > > > > > > > > > > > > > > > > Main objective here not to > change > > >> the > > >> > > > > > existing > > >> > > > > > > > > protocol > > >> > > > > > > > > > > > and > > >> > > > > > > > > > > > > > > still > > >> > > > > > > > > > > > > > > > > be able > > >> > > > > > > > > > > > > > > > > > > > > to write and read logs from > remote > > >> > storage. > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > -Harsha > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > On Feb 4, 2019, 2:53 PM -0800, > > >> Ryanne > > >> > > > > Dolan < > > >> > > > > > > > > > > > > > > > ryannedo...@gmail.com > > >> > > > > > > > > > > > > > > > > >, > > >> > > > > > > > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > Thanks Harsha, makes sense > for > > >> the > > >> > most > > >> > > > > > part. > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > tiered storage is to get > away > > >> > from this > > >> > > > > > and > > >> > > > > > > > > make > > >> > > > > > > > > > > this > > >> > > > > > > > > > > > > > > > > transparent to > > >> > > > > > > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > > > > > > user > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > I think you are saying that > this > > >> > enables > > >> > > > > > > > > additional > > >> > > > > > > > > > > > > > > > (potentially > > >> > > > > > > > > > > > > > > > > cheaper) > > >> > > > > > > > > > > > > > > > > > > > > > storage options without > > >> > *requiring* an > > >> > > > > > existing > > >> > > > > > > > > ETL > > >> > > > > > > > > > > > > > pipeline. > > >> > > > > > > > > > > > > > > > > But it's > > >> > > > > > > > > > > > > > > > > > > > > not > > >> > > > > > > > > > > > > > > > > > > > > > really a replacement for the > > >> sort > > >> > of > > >> > > > > > pipelines > > >> > > > > > > > > people > > >> > > > > > > > > > > > build > > >> > > > > > > > > > > > > > > > with > > >> > > > > > > > > > > > > > > > > Connect, > > >> > > > > > > > > > > > > > > > > > > > > > Gobblin etc. My point was > that, > > >> if > > >> > you > > >> > > > > are > > >> > > > > > > > > already > > >> > > > > > > > > > > > > > offloading > > >> > > > > > > > > > > > > > > > > records in > > >> > > > > > > > > > > > > > > > > > > > > an > > >> > > > > > > > > > > > > > > > > > > > > > ETL pipeline, why do you > need a > > >> new > > >> > > > > > pipeline > > >> > > > > > > > > built > > >> > > > > > > > > > > > into the > > >> > > > > > > > > > > > > > > > > broker to > > >> > > > > > > > > > > > > > > > > > > > > ship > > >> > > > > > > > > > > > > > > > > > > > > > the same data to the same > > >> place? I > > >> > think > > >> > > > > > in most > > >> > > > > > > > > > > cases > > >> > > > > > > > > > > > this > > >> > > > > > > > > > > > > > > > will > > >> > > > > > > > > > > > > > > > > be an > > >> > > > > > > > > > > > > > > > > > > > > > additional pipeline, not a > > >> > replacement, > > >> > > > > > because > > >> > > > > > > > > the > > >> > > > > > > > > > > > > > segments > > >> > > > > > > > > > > > > > > > > written to > > >> > > > > > > > > > > > > > > > > > > > > > cold storage won't be useful > > >> > outside > > >> > > > > > Kafka. So > > >> > > > > > > > > you'd > > >> > > > > > > > > > > > end up > > >> > > > > > > > > > > > > > > > with > > >> > > > > > > > > > > > > > > > > one of > > >> > > > > > > > > > > > > > > > > > > > > 1) > > >> > > > > > > > > > > > > > > > > > > > > > cold segments are only > useful to > > >> > Kafka; > > >> > > > > 2) > > >> > > > > > you > > >> > > > > > > > > have > > >> > > > > > > > > > > the > > >> > > > > > > > > > > > > > same > > >> > > > > > > > > > > > > > > > > data written > > >> > > > > > > > > > > > > > > > > > > > > > to HDFS/etc twice, once for > > >> Kafka > > >> > and > > >> > > > > once > > >> > > > > > for > > >> > > > > > > > > > > > everything > > >> > > > > > > > > > > > > > > else, > > >> > > > > > > > > > > > > > > > > in two > > >> > > > > > > > > > > > > > > > > > > > > > separate formats; 3) you use > > >> your > > >> > > > > existing > > >> > > > > > ETL > > >> > > > > > > > > > > > pipeline and > > >> > > > > > > > > > > > > > > > read > > >> > > > > > > > > > > > > > > > > cold > > >> > > > > > > > > > > > > > > > > > > > > data > > >> > > > > > > > > > > > > > > > > > > > > > directly. > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > To me, an ideal solution > would > > >> let > > >> > me > > >> > > > > spool > > >> > > > > > > > > segments > > >> > > > > > > > > > > > from > > >> > > > > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > to any > > >> > > > > > > > > > > > > > > > > > > > > sink > > >> > > > > > > > > > > > > > > > > > > > > > I would like, and then let > Kafka > > >> > clients > > >> > > > > > > > > seamlessly > > >> > > > > > > > > > > > access > > >> > > > > > > > > > > > > > > that > > >> > > > > > > > > > > > > > > > > cold > > >> > > > > > > > > > > > > > > > > > > > > data. > > >> > > > > > > > > > > > > > > > > > > > > > Today I can do that in the > > >> client, > > >> > but > > >> > > > > > ideally > > >> > > > > > > > > the > > >> > > > > > > > > > > > broker > > >> > > > > > > > > > > > > > > would > > >> > > > > > > > > > > > > > > > > do it for > > >> > > > > > > > > > > > > > > > > > > > > > me via some HDFS/Hive/S3 > plugin. > > >> > The KIP > > >> > > > > > seems to > > >> > > > > > > > > > > > > > accomplish > > >> > > > > > > > > > > > > > > > > that -- just > > >> > > > > > > > > > > > > > > > > > > > > > without leveraging anything > I've > > >> > > > > currently > > >> > > > > > got in > > >> > > > > > > > > > > > place. > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > Ryanne > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > On Mon, Feb 4, 2019 at 3:34 > PM > > >> > Harsha < > > >> > > > > > > > > > > ka...@harsha.io > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > Hi Eric, > > >> > > > > > > > > > > > > > > > > > > > > > > Thanks for your questions. > > >> > Answers are > > >> > > > > > in-line > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > "The high-level design > seems > > >> to > > >> > > > > indicate > > >> > > > > > that > > >> > > > > > > > > all > > >> > > > > > > > > > > of > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > logic > > >> > > > > > > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > > > > > > > when and > > >> > > > > > > > > > > > > > > > > > > > > > > how to copy log segments > to > > >> > remote > > >> > > > > > storage > > >> > > > > > > > > lives in > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > RLM > > >> > > > > > > > > > > > > > > > > class. The > > >> > > > > > > > > > > > > > > > > > > > > > > default implementation is > then > > >> > HDFS > > >> > > > > > specific > > >> > > > > > > > > with > > >> > > > > > > > > > > > > > > additional > > >> > > > > > > > > > > > > > > > > > > > > > > implementations being > left to > > >> the > > >> > > > > > community. > > >> > > > > > > > > This > > >> > > > > > > > > > > > seems > > >> > > > > > > > > > > > > > > like > > >> > > > > > > > > > > > > > > > > it would > > >> > > > > > > > > > > > > > > > > > > > > > > require anyone > implementing a > > >> > new RLM > > >> > > > > to > > >> > > > > > also > > >> > > > > > > > > > > > > > re-implement > > >> > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > logic > > >> > > > > > > > > > > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > > > > > > > > > when to ship data to > remote > > >> > storage." > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > RLM will be responsible > for > > >> > shipping > > >> > > > > log > > >> > > > > > > > > segments > > >> > > > > > > > > > > > and it > > >> > > > > > > > > > > > > > > will > > >> > > > > > > > > > > > > > > > > decide > > >> > > > > > > > > > > > > > > > > > > > > when > > >> > > > > > > > > > > > > > > > > > > > > > > a log segment is ready to > be > > >> > shipped > > >> > > > > > over. > > >> > > > > > > > > > > > > > > > > > > > > > > Once a Log Segement(s) are > > >> > identified > > >> > > > > as > > >> > > > > > rolled > > >> > > > > > > > > > > > over, RLM > > >> > > > > > > > > > > > > > > > will > > >> > > > > > > > > > > > > > > > > delegate > > >> > > > > > > > > > > > > > > > > > > > > > > this responsibility to a > > >> > pluggable > > >> > > > > remote > > >> > > > > > > > > storage > > >> > > > > > > > > > > > > > > > > implementation. > > >> > > > > > > > > > > > > > > > > > > > > Users who > > >> > > > > > > > > > > > > > > > > > > > > > > are looking add their own > > >> > > > > implementation > > >> > > > > > to > > >> > > > > > > > > enable > > >> > > > > > > > > > > > other > > >> > > > > > > > > > > > > > > > > storages all > > >> > > > > > > > > > > > > > > > > > > > > they > > >> > > > > > > > > > > > > > > > > > > > > > > need to do is to > implement the > > >> > copy and > > >> > > > > > read > > >> > > > > > > > > > > > mechanisms > > >> > > > > > > > > > > > > > and > > >> > > > > > > > > > > > > > > > > not to > > >> > > > > > > > > > > > > > > > > > > > > > > re-implement RLM itself. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > "Would it not be better > for > > >> the > > >> > Remote > > >> > > > > > Log > > >> > > > > > > > > Manager > > >> > > > > > > > > > > > > > > > > implementation to be > > >> > > > > > > > > > > > > > > > > > > > > > > non-configurable, and > instead > > >> > have an > > >> > > > > > > > > interface for > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > remote > > >> > > > > > > > > > > > > > > > > storage > > >> > > > > > > > > > > > > > > > > > > > > > > layer? That way the > "when" of > > >> > the logic > > >> > > > > > is > > >> > > > > > > > > > > consistent > > >> > > > > > > > > > > > > > > across > > >> > > > > > > > > > > > > > > > > all > > >> > > > > > > > > > > > > > > > > > > > > > > implementations and it's > only > > >> a > > >> > matter > > >> > > > > of > > >> > > > > > > > > "how," > > >> > > > > > > > > > > > similar > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > how the > > >> > > > > > > > > > > > > > > > > > > > > Streams > > >> > > > > > > > > > > > > > > > > > > > > > > StateStores are managed." > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > It's possible that we can > RLM > > >> > > > > > > > > non-configurable. But > > >> > > > > > > > > > > > for > > >> > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > initial > > >> > > > > > > > > > > > > > > > > > > > > > > release and to keep the > > >> backward > > >> > > > > > compatibility > > >> > > > > > > > > > > > > > > > > > > > > > > we want to make this > > >> > configurable and > > >> > > > > > for any > > >> > > > > > > > > users > > >> > > > > > > > > > > > who > > >> > > > > > > > > > > > > > > might > > >> > > > > > > > > > > > > > > > > not be > > >> > > > > > > > > > > > > > > > > > > > > > > interested in having the > > >> > LogSegments > > >> > > > > > shipped to > > >> > > > > > > > > > > > remote, > > >> > > > > > > > > > > > > > > they > > >> > > > > > > > > > > > > > > > > don't > > >> > > > > > > > > > > > > > > > > > > > > need to > > >> > > > > > > > > > > > > > > > > > > > > > > worry about this. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > Hi Ryanne, > > >> > > > > > > > > > > > > > > > > > > > > > > Thanks for your questions. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > "How could this be used to > > >> > leverage > > >> > > > > fast > > >> > > > > > > > > key-value > > >> > > > > > > > > > > > > > stores, > > >> > > > > > > > > > > > > > > > e.g. > > >> > > > > > > > > > > > > > > > > > > > > Couchbase, > > >> > > > > > > > > > > > > > > > > > > > > > > which can serve individual > > >> > records but > > >> > > > > > maybe > > >> > > > > > > > > not > > >> > > > > > > > > > > > entire > > >> > > > > > > > > > > > > > > > > segments? Or > > >> > > > > > > > > > > > > > > > > > > > > is the > > >> > > > > > > > > > > > > > > > > > > > > > > idea to only support > writing > > >> and > > >> > > > > fetching > > >> > > > > > > > > entire > > >> > > > > > > > > > > > > > segments? > > >> > > > > > > > > > > > > > > > > Would it > > >> > > > > > > > > > > > > > > > > > > > > make > > >> > > > > > > > > > > > > > > > > > > > > > > sense to support both?" > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > LogSegment once its rolled > > >> over > > >> > are > > >> > > > > > immutable > > >> > > > > > > > > > > > objects and > > >> > > > > > > > > > > > > > > we > > >> > > > > > > > > > > > > > > > > want to > > >> > > > > > > > > > > > > > > > > > > > > keep > > >> > > > > > > > > > > > > > > > > > > > > > > the current structure of > > >> > LogSegments > > >> > > > > and > > >> > > > > > > > > > > > corresponding > > >> > > > > > > > > > > > > > > Index > > >> > > > > > > > > > > > > > > > > files. It > > >> > > > > > > > > > > > > > > > > > > > > will > > >> > > > > > > > > > > > > > > > > > > > > > > be easy to copy the whole > > >> > segment as it > > >> > > > > > is, > > >> > > > > > > > > instead > > >> > > > > > > > > > > > of > > >> > > > > > > > > > > > > > > > > re-reading each > > >> > > > > > > > > > > > > > > > > > > > > file > > >> > > > > > > > > > > > > > > > > > > > > > > and use a key/value store. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > " > > >> > > > > > > > > > > > > > > > > > > > > > > - Instead of defining a > new > > >> > interface > > >> > > > > > and/or > > >> > > > > > > > > > > > mechanism to > > >> > > > > > > > > > > > > > > ETL > > >> > > > > > > > > > > > > > > > > segment > > >> > > > > > > > > > > > > > > > > > > > > files > > >> > > > > > > > > > > > > > > > > > > > > > > from brokers to cold > storage, > > >> > can we > > >> > > > > just > > >> > > > > > > > > leverage > > >> > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > itself? In > > >> > > > > > > > > > > > > > > > > > > > > > > particular, we can > already ETL > > >> > records > > >> > > > > > to HDFS > > >> > > > > > > > > via > > >> > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > Connect, > > >> > > > > > > > > > > > > > > > > > > > > Gobblin > > >> > > > > > > > > > > > > > > > > > > > > > > etc -- we really just > need a > > >> way > > >> > for > > >> > > > > > brokers to > > >> > > > > > > > > > > read > > >> > > > > > > > > > > > > > these > > >> > > > > > > > > > > > > > > > > records > > >> > > > > > > > > > > > > > > > > > > > > back. > > >> > > > > > > > > > > > > > > > > > > > > > > I'm wondering whether the > new > > >> > API could > > >> > > > > > be > > >> > > > > > > > > limited > > >> > > > > > > > > > > > to the > > >> > > > > > > > > > > > > > > > > fetch, and > > >> > > > > > > > > > > > > > > > > > > > > then > > >> > > > > > > > > > > > > > > > > > > > > > > existing ETL pipelines > could > > >> be > > >> > more > > >> > > > > > easily > > >> > > > > > > > > > > > leveraged. > > >> > > > > > > > > > > > > > For > > >> > > > > > > > > > > > > > > > > example, if > > >> > > > > > > > > > > > > > > > > > > > > you > > >> > > > > > > > > > > > > > > > > > > > > > > already have an ETL > pipeline > > >> > from Kafka > > >> > > > > > to > > >> > > > > > > > > HDFS, > > >> > > > > > > > > > > you > > >> > > > > > > > > > > > > > could > > >> > > > > > > > > > > > > > > > > leave that > > >> > > > > > > > > > > > > > > > > > > > > in > > >> > > > > > > > > > > > > > > > > > > > > > > place and just tell Kafka > how > > >> to > > >> > read > > >> > > > > > these > > >> > > > > > > > > > > > > > > records/segments > > >> > > > > > > > > > > > > > > > > from cold > > >> > > > > > > > > > > > > > > > > > > > > > > storage when necessary." > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > This is pretty much what > > >> > everyone does > > >> > > > > > and it > > >> > > > > > > > > has > > >> > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > additional > > >> > > > > > > > > > > > > > > > > > > > > overhead > > >> > > > > > > > > > > > > > > > > > > > > > > of keeping these pipelines > > >> > operating > > >> > > > > and > > >> > > > > > > > > > > monitoring. > > >> > > > > > > > > > > > > > > > > > > > > > > What's proposed in the > KIP is > > >> > not ETL. > > >> > > > > > It's > > >> > > > > > > > > just > > >> > > > > > > > > > > > looking > > >> > > > > > > > > > > > > > a > > >> > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > logs > > >> > > > > > > > > > > > > > > > > > > > > that > > >> > > > > > > > > > > > > > > > > > > > > > > are written and rolled > over to > > >> > copy the > > >> > > > > > file > > >> > > > > > > > > as it > > >> > > > > > > > > > > > is. > > >> > > > > > > > > > > > > > > > > > > > > > > Each new topic needs to be > > >> added > > >> > (sure > > >> > > > > > we can > > >> > > > > > > > > do so > > >> > > > > > > > > > > > via > > >> > > > > > > > > > > > > > > > > wildcard or > > >> > > > > > > > > > > > > > > > > > > > > > > another mechanism) but new > > >> > topics need > > >> > > > > > to be > > >> > > > > > > > > > > onboard > > >> > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > ship > > >> > > > > > > > > > > > > > > > > the data > > >> > > > > > > > > > > > > > > > > > > > > into > > >> > > > > > > > > > > > > > > > > > > > > > > remote storage through a > > >> > traditional > > >> > > > > ETL > > >> > > > > > > > > pipeline. > > >> > > > > > > > > > > > > > > > > > > > > > > Once the data lands > somewhere > > >> > like > > >> > > > > > HDFS/HIVE > > >> > > > > > > > > etc.. > > >> > > > > > > > > > > > Users > > >> > > > > > > > > > > > > > > need > > >> > > > > > > > > > > > > > > > > to write > > >> > > > > > > > > > > > > > > > > > > > > > > another processing line to > > >> > re-process > > >> > > > > > this data > > >> > > > > > > > > > > > similar > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > how > > >> > > > > > > > > > > > > > > > > they are > > >> > > > > > > > > > > > > > > > > > > > > > > doing it in their Stream > > >> > processing > > >> > > > > > pipelines. > > >> > > > > > > > > > > Tiered > > >> > > > > > > > > > > > > > > storage > > >> > > > > > > > > > > > > > > > > is to get > > >> > > > > > > > > > > > > > > > > > > > > > > away from this and make > this > > >> > > > > transparent > > >> > > > > > to the > > >> > > > > > > > > > > user. > > >> > > > > > > > > > > > > > They > > >> > > > > > > > > > > > > > > > > don't need > > >> > > > > > > > > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > > > > > > > run another ETL process to > > >> ship > > >> > the > > >> > > > > logs. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > "I'm wondering if we could > > >> just > > >> > add > > >> > > > > > support for > > >> > > > > > > > > > > > loading > > >> > > > > > > > > > > > > > > > > segments from > > >> > > > > > > > > > > > > > > > > > > > > > > remote URIs instead of > from > > >> > file, i.e. > > >> > > > > > via > > >> > > > > > > > > plugins > > >> > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > s3://, > > >> > > > > > > > > > > > > > > > > hdfs:// > > >> > > > > > > > > > > > > > > > > > > > > etc. > > >> > > > > > > > > > > > > > > > > > > > > > > I suspect less broker > logic > > >> would > > >> > > > > change > > >> > > > > > in > > >> > > > > > > > > that > > >> > > > > > > > > > > > case -- > > >> > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > broker > > >> > > > > > > > > > > > > > > > > > > > > > > wouldn't necessarily care > if > > >> it > > >> > reads > > >> > > > > > from > > >> > > > > > > > > file:// > > >> > > > > > > > > > > or > > >> > > > > > > > > > > > > > s3:// > > >> > > > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > load a > > >> > > > > > > > > > > > > > > > > > > > > given > > >> > > > > > > > > > > > > > > > > > > > > > > segment." > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > Yes, this is what we are > > >> > discussing in > > >> > > > > > KIP. We > > >> > > > > > > > > are > > >> > > > > > > > > > > > > > leaving > > >> > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > details > > >> > > > > > > > > > > > > > > > > > > > > of > > >> > > > > > > > > > > > > > > > > > > > > > > loading segments to RLM > read > > >> part > > >> > > > > > instead of > > >> > > > > > > > > > > directly > > >> > > > > > > > > > > > > > > > exposing > > >> > > > > > > > > > > > > > > > > this in > > >> > > > > > > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > > > > > > > Broker. This way we can > keep > > >> the > > >> > > > > current > > >> > > > > > Kafka > > >> > > > > > > > > code > > >> > > > > > > > > > > > as it > > >> > > > > > > > > > > > > > > is > > >> > > > > > > > > > > > > > > > > without > > >> > > > > > > > > > > > > > > > > > > > > > > changing the assumptions > > >> around > > >> > the > > >> > > > > local > > >> > > > > > > > > disk. Let > > >> > > > > > > > > > > > the > > >> > > > > > > > > > > > > > RLM > > >> > > > > > > > > > > > > > > > > handle the > > >> > > > > > > > > > > > > > > > > > > > > > > remote storage part. > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > > > > > > > > > > > > Harsha > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > On Mon, Feb 4, 2019, at > 12:54 > > >> PM, > > >> > > > > Ryanne > > >> > > > > > Dolan > > >> > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > > > Harsha, Sriharsha, > Suresh, a > > >> > couple > > >> > > > > > thoughts: > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > - How could this be > used to > > >> > leverage > > >> > > > > > fast > > >> > > > > > > > > > > key-value > > >> > > > > > > > > > > > > > > stores, > > >> > > > > > > > > > > > > > > > > e.g. > > >> > > > > > > > > > > > > > > > > > > > > > > Couchbase, > > >> > > > > > > > > > > > > > > > > > > > > > > > which can serve > individual > > >> > records > > >> > > > > but > > >> > > > > > maybe > > >> > > > > > > > > not > > >> > > > > > > > > > > > entire > > >> > > > > > > > > > > > > > > > > segments? Or > > >> > > > > > > > > > > > > > > > > > > > > is > > >> > > > > > > > > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > > > > > > > > idea to only support > writing > > >> > and > > >> > > > > > fetching > > >> > > > > > > > > entire > > >> > > > > > > > > > > > > > > segments? > > >> > > > > > > > > > > > > > > > > Would it > > >> > > > > > > > > > > > > > > > > > > > > make > > >> > > > > > > > > > > > > > > > > > > > > > > > sense to support both? > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > - Instead of defining a > new > > >> > interface > > >> > > > > > and/or > > >> > > > > > > > > > > > mechanism > > >> > > > > > > > > > > > > > to > > >> > > > > > > > > > > > > > > > > ETL segment > > >> > > > > > > > > > > > > > > > > > > > > > > files > > >> > > > > > > > > > > > > > > > > > > > > > > > from brokers to cold > > >> storage, > > >> > can we > > >> > > > > > just > > >> > > > > > > > > > > leverage > > >> > > > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > itself? In > > >> > > > > > > > > > > > > > > > > > > > > > > > particular, we can > already > > >> ETL > > >> > > > > records > > >> > > > > > to > > >> > > > > > > > > HDFS > > >> > > > > > > > > > > via > > >> > > > > > > > > > > > > > Kafka > > >> > > > > > > > > > > > > > > > > Connect, > > >> > > > > > > > > > > > > > > > > > > > > Gobblin > > >> > > > > > > > > > > > > > > > > > > > > > > > etc -- we really just > need a > > >> > way for > > >> > > > > > brokers > > >> > > > > > > > > to > > >> > > > > > > > > > > > read > > >> > > > > > > > > > > > > > > these > > >> > > > > > > > > > > > > > > > > records > > >> > > > > > > > > > > > > > > > > > > > > back. > > >> > > > > > > > > > > > > > > > > > > > > > > > I'm wondering whether > the > > >> new > > >> > API > > >> > > > > > could be > > >> > > > > > > > > > > limited > > >> > > > > > > > > > > > to > > >> > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > fetch, and > > >> > > > > > > > > > > > > > > > > > > > > then > > >> > > > > > > > > > > > > > > > > > > > > > > > existing ETL pipelines > could > > >> > be more > > >> > > > > > easily > > >> > > > > > > > > > > > leveraged. > > >> > > > > > > > > > > > > > > For > > >> > > > > > > > > > > > > > > > > example, > > >> > > > > > > > > > > > > > > > > > > > > if > > >> > > > > > > > > > > > > > > > > > > > > > > you > > >> > > > > > > > > > > > > > > > > > > > > > > > already have an ETL > pipeline > > >> > from > > >> > > > > > Kafka to > > >> > > > > > > > > HDFS, > > >> > > > > > > > > > > > you > > >> > > > > > > > > > > > > > > could > > >> > > > > > > > > > > > > > > > > leave > > >> > > > > > > > > > > > > > > > > > > > > that in > > >> > > > > > > > > > > > > > > > > > > > > > > > place and just tell > Kafka > > >> how > > >> > to read > > >> > > > > > these > > >> > > > > > > > > > > > > > > > records/segments > > >> > > > > > > > > > > > > > > > > from > > >> > > > > > > > > > > > > > > > > > > > > cold > > >> > > > > > > > > > > > > > > > > > > > > > > > storage when necessary. > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > - I'm wondering if we > could > > >> > just add > > >> > > > > > support > > >> > > > > > > > > for > > >> > > > > > > > > > > > > > loading > > >> > > > > > > > > > > > > > > > > segments > > >> > > > > > > > > > > > > > > > > > > > > from > > >> > > > > > > > > > > > > > > > > > > > > > > > remote URIs instead of > from > > >> > file, > > >> > > > > i.e. > > >> > > > > > via > > >> > > > > > > > > > > plugins > > >> > > > > > > > > > > > for > > >> > > > > > > > > > > > > > > > > s3://, hdfs:// > > >> > > > > > > > > > > > > > > > > > > > > > > etc. > > >> > > > > > > > > > > > > > > > > > > > > > > > I suspect less broker > logic > > >> > would > > >> > > > > > change in > > >> > > > > > > > > that > > >> > > > > > > > > > > > case > > >> > > > > > > > > > > > > > -- > > >> > > > > > > > > > > > > > > > the > > >> > > > > > > > > > > > > > > > > broker > > >> > > > > > > > > > > > > > > > > > > > > > > > wouldn't necessarily > care if > > >> > it reads > > >> > > > > > from > > >> > > > > > > > > > > file:// > > >> > > > > > > > > > > > or > > >> > > > > > > > > > > > > > > s3:// > > >> > > > > > > > > > > > > > > > > to load a > > >> > > > > > > > > > > > > > > > > > > > > > > given > > >> > > > > > > > > > > > > > > > > > > > > > > > segment. > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > Combining the previous > two > > >> > comments, > > >> > > > > I > > >> > > > > > can > > >> > > > > > > > > > > imagine > > >> > > > > > > > > > > > a > > >> > > > > > > > > > > > > > URI > > >> > > > > > > > > > > > > > > > > resolution > > >> > > > > > > > > > > > > > > > > > > > > chain > > >> > > > > > > > > > > > > > > > > > > > > > > > for segments. For > example, > > >> > first try > > >> > > > > > > > > > > > > > > > > > > > > > > >> file:///logs/{topic}/{segment}.log, > > >> > > > > > > > > > > > > > > > > > > > > > > > then > > >> > > > > > > > > s3://mybucket/{topic}/{date}/{segment}.log, > > >> > > > > > > > > > > > etc, > > >> > > > > > > > > > > > > > > > > leveraging your > > >> > > > > > > > > > > > > > > > > > > > > > > > existing ETL > pipeline(s). > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > Ryanne > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > On Mon, Feb 4, 2019 at > > >> 12:01 PM > > >> > > > > Harsha > > >> > > > > > < > > >> > > > > > > > > > > > > > ka...@harsha.io> > > >> > > > > > > > > > > > > > > > > wrote: > > >> > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > Hi All, > > >> > > > > > > > > > > > > > > > > > > > > > > > > We are interested in > > >> adding > > >> > tiered > > >> > > > > > storage > > >> > > > > > > > > to > > >> > > > > > > > > > > > Kafka. > > >> > > > > > > > > > > > > > > More > > >> > > > > > > > > > > > > > > > > > > > > > > details > > >> > > > > > > > > > > > > > > > > > > > > > > > > about motivation and > > >> design > > >> > are in > > >> > > > > > the > > >> > > > > > > > > KIP. We > > >> > > > > > > > > > > > are > > >> > > > > > > > > > > > > > > > working > > >> > > > > > > > > > > > > > > > > towards > > >> > > > > > > > > > > > > > > > > > > > > an > > >> > > > > > > > > > > > > > > > > > > > > > > > > initial POC. Any > feedback > > >> or > > >> > > > > > questions on > > >> > > > > > > > > this > > >> > > > > > > > > > > > KIP > > >> > > > > > > > > > > > > > are > > >> > > > > > > > > > > > > > > > > welcome. > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > Thanks, > > >> > > > > > > > > > > > > > > > > > > > > > > > > Harsha > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > >> > > > >
